BS7671:2018 Proposed Changes

[Ian1981]

Does actually any other European country use tncs?
Always thought it was a uk thing

 

[Rpa07]

Are there any statistics regarding the failing of PEN conductors and their occurances?
There surely are monitoring systems available to DNOs for these occurances leading to rapid responses.
I thought that TNCS was the future but if wrought with SO MUCH DANGER and the possible need for earth rod back up at every install, it strikes me as not that advanced!

 

[Andy78]

My initial thought is that if this is felt necessary as a requirement for safety due to the nature of the incoming supply, should this not be introduced into ESCQR and not have the onus for this safety measure put upon the end user ?

 

[davesparks]

Are there any statistics regarding the failing of PEN conductors and their occurances?
There surely are monitoring systems available to DNOs for these occurances leading to rapid responses.
I thought that TNCS was the future but if wrought with SO MUCH DANGER and the possible need for earth rod back up at every install, it strikes me as not that advanced!

Tncs is the future because it's cheaper to install, that's the main driving force behind its use.
Nobody is saying that there is SO MUCH DANGER, just that there is a danger and it should be mitigated.

 

[davesparks]

My initial thought is that if this is felt necessary as a requirement for safety due to the nature of the incoming supply, should this not be introduced into ESCQR and not have the onus for this safety measure put upon the end user ?

Increased csa of main bonding is a requirement for safety due to the nature of the incoming supply (PME) as is the use of rcds for fault protection (TT), nobody expects the DNOs to foot the bill for it so why should this be any different?

 

[Andy78]

Increased csa of main bonding is a requirement for safety due to the nature of the incoming supply (PME) as is the use of rcds for fault protection (TT), nobody expects the DNOs to foot the bill for it so why should this be any different?

Yeah good point.

I hope guidance is brought out as to what is expected of an installed electrode for these purposes though. Round these parts a 3/8" rod bashed halfway into the mud and rubble under the floor under the stairs seems to constitute a permanent TT arrangement when the sparky can't be bothered to call the DNO and wait a couple of weeks for a connection.

 

[Ian1981]

Increased csa of main bonding is a requirement for safety due to the nature of the incoming supply (PME) as is the use of rcds for fault protection (TT), nobody expects the DNOs to foot the bill for it so why should this be any different?

Then why not do away with that possible problem and go back to TN-S?
Cost is the reason pure and simple.
no risk of raising the earth to mains potential due to open pen conductor and no diverted neutral currents.
Earth can still fail of course.

 

[telectrix]

sod it. i'm going back to the 16th. RCDs only where sensibly required, CUs didn't spontaneously combust, no 5wws, shared neutrals save cable, no cat 5 run everywhere, sound in every room created by leaving doors open and turning the volume up. and only 4 channels of garbage on the telly instead of 200 . good old days.

 

[Pete999]

sod it. i'm going back to the 16th. RCDs only where sensibly required, CUs didn't spontaneously combust, no 5wws, shared neutrals save cable, no cat 5 run everywhere, sound in every room created by leaving doors open and turning the volume up. and only 4 channels of garbage on the telly instead of 200 . good old days.

BBC1 BBC2 ITV and C4 if you were lucky Apprenticeships, Plastic CUs and on and on and on. Glad I'm out to grass, or out to Red Vino, never did like grass, gives me Hay Fever, as well as a hangover. Tried that Mid Eartern stuff once Gaaat I think it was bit like a Privet hedge.

 

[Pat H]

Further to my post on the other thread can anyone find anything about AFDD's and where they will be required, other than they may be fitted!

How an Arc Fault Detection Devices (AFDD) can prevent electrical fire? - http://blog.schneider-electric.com/power-management-metering-monitoring-power-quality/2013/07/03/do-you-know-an-arc-fault-detection-device-afdd-can-prevent-from-an-electrical-fire/

 

[davesparks]

Then why not do away with that possible problem and go back to TN-S?
Cost is the reason pure and simple.
no risk of raising the earth to mains potential due to open pen conductor and no diverted neutral currents.
Earth can still fail of course.

I would imagine the fact that it is almost impossible to do that would have something to do with it.
Also a TNS system these days would not be as good as it was due to the type of cable used these days. The old TNS systems relied in part on the lead sheath being in contact with the earth and forming one large earth electrode, modern plastic insulated cables won't offer this advantage.
And as you say, the earth can still fail.

 

[Toneyz]

I love how the supply authorities issue becomes the installers problem!

But remember that the supplier does not have to provide a earth facility.

 

[Pete999]

But remember that the supplier does not have to provide a earth facility.

Yes the reason for this edict is the failing of older U/G cables or degrading with age

 

[Flanders]

Will be interesting seeing how many domestic installions get condemned for no earth rods, I noticed that now all lighting circuits in domestic installations will have to be rcd protected which is just belt and braces to make sure rcds are fitted on all circuits in a house .

 

[Ian1981]

Ca

But remember that the supplier does not have to provide a earth facility.

but 99% of the time they will unless there's a good reason not to

 

[Toneyz]

What happens if you live in a block of flats ? or if your posh apartments

 

[Andy78]

Will be interesting seeing how many domestic installions get condemned for no earth rods, I noticed that now all lighting circuits in domestic installations will have to be rcd protected which is just belt and braces to make sure rcds are fitted on all circuits in a house .

I can still think of plenty of types of circuits that have no requirement for RCD protection, installation method dependant of course.

 

[Andy78]

What happens if you live in a block of flats ? or if your posh apartments

Flat below will have to find a use for the copper coated ceiling decoration they now have.

 

[davesparks]

What happens if you live in a block of flats ? or if your posh apartments

Well the sensible people will install earth electrodes connected to the MET of the incoming supply to the building.

The less sensible people will be clipping green and yellow cables down the outside of the building to earth rods.

 

[Andy78]

Well the sensible people will install earth electrodes connected to the MET of the incoming supply to the building.

The less sensible people will be clipping green and yellow cables down the outside of the building to earth rods.

Hahahaha can just imagine that. One for each flat